Comparing regulated and unregulated airguns

What is a regulator?First, what is a regulator and how does it work? A firing valve in a PCP does not operate at its peak at 3,000 psi–not even close. Most of them work best down around 2,000 psi and some work best at even lower pressure. But, the fact is that they still do work acceptably well at higher pressure. So, the gun gives a string of shots at a more or less constant velocity until it drops below the lowest pressure at which the valve functions well.

Valve lockJust above the top-end operating pressure, the valve starts closing sooner than it should. When a certain pressure is exceeded, the gun begins to shoot slower than it’s capable of shooting. It continues to do this until the internal pressure drops below the point where valve lock starts happening.

An air valve has a range of pressure–from low to high. As long as the air that’s supplied to it stays within that range, the gun shoots at a constant velocity, more or less. And it’s the “more or less” that’s of great concern to airgunners.

An unregulated gunI have a Daystate Harrier that operates best between 2650 psi and 2,000 psi. In that range, I get 24 shots of 10.6-grain Beeman Kodiaks going about 920 f.p.s. They will not vary more than 20 f.p.s. throughout the entire range. But fill to 2700 psi, and the pellet might go only 880 f.p.s. for the first two or three shots. Continue shooting after the 24 good shots (pressure falling below 2000 psi), and the velocity drops again into the 800s.

That is what a fairly good unregulated gun will do. I’ve seen better ones that would keep their strings within 10 f.p.s. throughout the range. All valves are not of equal quality and stability. I’ve also seen valves that varied more throughout their range. The AirForce Talon SS will often vary by 30 f.p.s. throughout its range, yet still shoots half-inch 5-shot groups at 50 yards.

A regulated gunWhat about a regulated gun? Well, a regulator lowers the pressure of the reservoir to an ideal level before making it available to the valve. You might want to read my report on the air pressure regulator. If I installed a regulator in the reservoir of my Harrier, I could probably drop the velocity variation within the string of shots from 20 f.p.s. down to 10 f.p.s. or, perhaps, even less. I’ve tested PCP guns that varied by only two f.p.s. throughout their entire string of usable shots.

However, by installing a pressure regulator with its firing chamber inside the reservoir of my Harrier, I’d be subtracting volume from the reservoir. In other words, less room for air. That could be offset by increasing the pressure in the reservoir, but there’s a point beyond which the regulator will not operate. So you can’t just keep increasing the pressure indefinitely.

What are the benefits?How would I benefit if I installed a reg in the Harrier? Well, quite probably I would pick up a shot or two. Experience shows that with small reservoirs, like the one in the Harrier, a reg will add only a shot or two to the total string. And all the shots would be closer in velocity because the firing valve would be working at the ideal pressure. The question I have to answer is if I think it’s worth a couple extra shots and a slightly tighter velocity variation to go to the trouble of installing a regulator.

I decided that it wasn’t, because my Harrier operates at a nice low max pressure. It’s easy to pump to 2650 psi; much easier than to pump to 3,000 psi. At least, it is for me.

On the other hand, my Career 707 went from 30 usable shots to over 60 at the same power with a regulator. And the velocity variation of those shots dropped from over 30 f.p.s. to around 10 f.p.s. In that case, it was definitely worth the effort to install the reg.

Some things to considerSome guns aren’t suited for regulators. The AirForce guns, for example, cannot be easily regulated because of how their tanks are made. Any regulator would have to be external to the tank, which would add to the rifle’s length of pull. The Benjamin Discovery has a small reservoir like the Harrier, so adding a regulator might not gain an advantage in total shots, but it might tighten the extreme spread of the string, which is on the order of 30-35 f.p.s. right now.

The final thing I want to say about regulators is they will all fail at some point. That’s a fact that cannot be denied. I’m not talking about decades of time, either. Regs are not known for lasting a long time. The greater the pressure differential (difference between reservoir pressure and firing pressure) they must deal with, the shorter their life tends to be. When they go, you usually end up with an unregulated gun. In some cases, you have a broken gun that has to be repaired to work at all.

The USFTFor that reason, Larry Durham decided not to regulate the design of what became the USFT rifle. He felt it’s better to have an easily repairable rifle than to have a super-tight velocity spread. The USFT won the 2007 Field Target World Championship.

Here are my personal feelings. I like regulators on 10-meter guns, where they seem to last a long time. But on a sporting airgun, I like an unregulated but balanced valve that I know will outlast any regulator. However, when the reg is working, it makes for a wonderful airgun experience. I cannot deny that.

52 thoughts on “Comparing regulated and unregulated airguns”

Thanks so much for this topic. This is perfect information for someone, like me, considering an entrance into the pcp world of airgunning.

Does a shot string in a pcp that varies more than 30 fps affect accuracy normally? You mentioned that although air force guns vary by 30 fps their accuracy isn’t dramatically affected.

Is a power adjuster on a pcp prone to necessary constant maintenance like a regulator in a pcp?

I have read where some pcp’s have “after market” or newly designed “fast flow adaptors” and enlarged “thru-porting” that increases the number of shots between 50% and 150%. Are these modifications to the regulator like your article is talking about?

Hello B.B.:Thank you once again for helping me… Today I feel more relax and ready to work on things… Its good to know that the damaged hole can be fixed… I will call AirForce now and see what happens… About the bloop tube… nope, I don’t use one… Yesterday I only used the .22caliber 24″barrel, nothing else… Take care sir!!Cheers,Jony

First, about the guns that vary more than 30 f.p.s. Does it affect accuracy? Here are my observations.

If the gun is question is a small caliber (.177) and the pellet is light (below 9 grains), then probably the accuracy out at 50 yards would be affected by a variation of greater than 30 f.p.s.

If the caliber is large (.22) and the pellet is heavy (21-30 grains,) then the accuracy is not affected to a noticeable degree by velocity variations greater than 30 f.p.s.

A .22 long rifle often varies by more than 30 f.p.s. in a 10-shot string, yet the accuracy isn’t affected at 50 yards. I think that is because of the weight of the bullet. And so I will guess that a heavier pellet flies with less disruption as well.

Concerning the flow modifications you mention – they are valve modifications, not regulator mods. They change the way the firing valve performs, but not through regulating the starting air pressure.

On my three Air Arms, .177 S410 with power adjuster, .22 cal s410 without power adjuster and the older s310 without power adjuster, I can have a variation in FPS of 50 without measurable loss of POI, at 20 yards indoors.

On the .177 with power adjuster, and a 200 bar fill, I get 130 shots with a loss of 237 FPS (50 bar) the drop in POI is only 1/2″ at 20 yards indoors.

B.B.

Billy Lo with a USFT also won the 2005 nationals, and his prize was a 12 foot pound USFT specially tuned for the world championship. That one is in our inventory now.

With a 2000 pound fill, it gets 80 shots without measurable loss of POI (point of impact) at 20 yards indoors, more than enough for a contest….

Again, for me personally I find no problem dealing with a little loss of POI or valve lock… get to know your rifle and take more shots per fill. You need to adjust for wind anyway, so adjusting up and down is just practice for adjusting left and right, for the wind..

Valve lock can be a real problem if the gun is very tight. Sometimes they don’t leak down in months of sitting.

What has to be done is a partial disassembly of the firing mechanism, and the firing valve stem is struck with a hammer to exhaust some of the air. Care must be taken to now loosen the air reservoir at this time or the gun could explode!

B.B.: I spoke with a very nice lady in AirForce, she took my address… She is gonna send me a muzzle cap replacement screw first to see if it fits… if not, we’ll try something else… Now comes the waiting period…LOL… I am sure that the problem is the hole, but lets see… Take care!!Cheers,Jony

Thanks. Your answer makes sense. Weight of the pellet/bullet must play a role in accuracy even though you may have an above average spread of fps.

Do you like the power adjustment option on some pcp’s or is this just one more thing to maintain that isn’t worth it? In other words is a power adjuster on a pcp prone to necessary constant maintenance like a regulator in a pcp?

Wayne,

Very interesting. If I remember right the .177 S410 with power adjuster was your first and still is your favorite pcp? What setting do you have the power adjusted to in order to shoot 130 shots and only lose 237 fps (50 bar)? How many shots out of the 130 do you get with no loss in poi?

Do you know how to chase a cross-threaded hole with a screw? Insert the screw in the hole and lightly turn it counter-clockwise, as if you were removing it. When you feel the thread click into position, carefully tighten the screw in the other direction. If the threads are not damaged too bad, this will realign them. You can do this now, before the end cap arrives.

I like power adjustment on some guns, but not on others. And I don’t try to use it the way most people do. On AirForce guns, for example, I don’t even have a scale on my power wheel! So I never know what number I am setting the gun to. Yet I can get it where I want it every time.

Instead of 20 different adjustments, I look for the two or three that make a difference.

“Valved with FX’s latest design, this rifle delivers regulated performance without the hassle of a regulator.”

Still made me think maybe a regulator would be better – nice to see they are not really a necessity.

Kevin,

One of the huge concerns I had was the variance in velocity I would read about. Bless Wayne’s heart, but when he writes that he has just a “237 fps” variance and you’re use to 5-10 fps at the most from a spring rifle – it can have a negative effect.

But Wayne shoots his rifles down lower then most. It works for him, so that is great. What my research has shown is if a rifle has a 200 bar fill you stop at about 100 bar, the number of shots is different (air tube size, efficiency) but the variance will be much smaller in fps. Without a divers tank, it is faster to top of a rifle that way also.

If you get a PCP I would start out simple like with a Disco, or your own set up with the least equipment and features on the rifle.

I think part of the lesson in Jony’s experience is way too much stuff all at once. Different tanks, barrels, bloop tube, etc – too many variables.

My cost to try the Disco was just $38 for the 5 weeks I owned it. The old two shot Raider is about as complex to use as a rubber band gun.

JonyThis may be difficult, but possible.Position the screw inside the frame with a pair of tweezers or needle nose pliers. Insert the allen wrench through the screw hole and into the screw head. Find something to press against the bottom of the screw to get it up against the hole on the inside of the frame.See if the screw can be started with some threads that are hopefully remaining undamaged and turn the screw out through the frame.

A trick with with screws and bolts is the feel to them when they are starting right or wrong. When dealing with aluminum or any soft metal, all it takes is just a little force to damage if it is crossthreading.

They should spin in with finger force only. If they start to lock up before more than a turn or two is accomplished, then you better look for trouble.

Lone last note…If you snapped an allen wrench doing this, then you are using way too much force.

Jony, It’s great to hear the optomism in your key stokes again. If you have a real old fashon hardware store, you should be able to buy the screws you need there which is what I did for my SS.

B.B. Thanks for this post. As a powder powered rifle reloader and woodchuck shooter I spent alot of time trying to get absolute uniformity in all of my reloads. Chronnys weren’t availabe back in my reloading days so I couldn’t check velocities, but a couple of tenths of a grain of powder should could change group size which triggered my request for this topic.

My thinking was that the regulator is the powder measure that I used to use back in the day. If I had the same pressure and volume of air for each shot, everything else being equal, I would have a more accurate rifle. However, that does not seem to be the case or is 30fps variation not enough to matter? B.B. help again! and thanks.

Wayne, knowing your rifle is where it’s at. My Discovery has Anthony’s barrel weight, but I can still hear the change in sound when she is entering and leaving her sweet spot which is also reflected in the size of the groups. The Talon SS with Van’s bloop tube makes no noise except for the hammer ping, so I’m still in a learning curve there.

Mr. B.Run some numbers through chairgun.Compare a .22 with a low B.C. wadcutter at 600 fps to a .177 with a high B.C. heavy at 1000 fps for drop at 50 yards. Use some different velocity figures for each and look at the poi differences.You will find that the faster the pellet (or bullet) gets to the target, the less POI will be affected by velocity deviation.

This addresses POI change only, and not necessarily accuracy. It becomes evident that MV, BC, distance, and what you consider alowable POI change will have a big effect on shot count and allowable shot to shot variation in velocity.

Yeah, I come from the “before chrony” days of reloading, too. Back then it was good just to make an accurate round that didn’t blow up the gun.

When going for accuracy, airgunners are exactly like firearm reloaders. The goal is for zero variation from shot to shot. But what really influences accuracy is a greater variation than zero. The exact number depends on the gun, the pellet and the distance at which you are shooting. So your question really has no answer – just the general hope to do the best you can.

I started with a Disco last March, and added the .177 cal Air Arms S410 in June.

I like to keep the power adjuster at about half on the .177 S410. At half power, with a 200 bar fill, it shoots the JSB 10.2 heavy at 919fps hi, 908 lo, avg 911fps for the first 30 shots… on shot 60 I'm at 873fps on shot 90 I'm at 100 bar and 798fps….At 20 yards indoor first loss of poi is about shot 90.. maybe 1/8" low, shot 130 at 50 bar, (765fps) 1/2" low…I know my rifle and can adjust for that just fine… I CAN, (not always) keep a 3/8" – 5 shot group for all 130 shots in a benchrest..

B.B. and Twotalon: I tried exactly what both said, but I think I identified the problem… The threads are pretty damaged… The screw can enter only until midway, then it gets really hard… If I do what Twotalon said, it also gets stuck in the middle… I even tried putting in the other screws from the side and the others in the bottom even though they are different lengths, they got stuck midway… It has to be the hole…. I would have shipped the rifle (the frame only without the tank) to AirForce today but the lady wanted to try the new screw first… Not a bad idea to begin with… I don’t know if I told you how i managed to take out the front screw yesterday… I had to use a wrench to tightly hold the very little head of the screw that was poking out (since it was halfway screwed already and the tip of my tool was inserted in the screw)… and turn it… It took me 20 minutes,, wasn’t easy, and as I said, scratched the surface around the hole (with the wrench obviously)… I went to the range today with my G.Whisper and Benji397, no more stress.. LOL… Take care people… And thank youCheers,Jony

BB,Its starting to make sense, i.e. testing shot strings to find the sweet spot on an unregulated gun. I would be one of those that couldn’t stand a moving POI:). Guess I had better add a chrony to the wishlist before buying a PCP. I suspect also that the BC of the pellet would be about as important as the weight in minimizing POI shifts with velocity changes.

My experience with regulators comes from paintball. I have never seen a regulator fail, and I have been using the same primary regulator for 10 years. A primary regulator is a non-adjustable reg that is attached directly to the air reservoir. My reservoir is 92 cubic inches and is filled to 4500 psi. The primary reg reduces that pressure to 450psi.

The air flows into a secondary adjustable regulator that reduces air pressure to 290psi. It then moves to a volumeizer, then a flow regulator before launching the paintball at 290fps with a 3fps spread. It takes about the same volume of CO2 operating at 900psi to achieve the same velocity but the spread is inconsistent and often expands as rate of fire increases.

Most primary regulators outlast the 15 year shelf life of the reservoirs to which they are attached. They are often removed and attached to new reservoirs because it is cheaper than purchasing a completely new unit. especially if the primary and secondary regs are one in the same.

These regulators are usually large and traditionally double as hand grips. But they are very reliable. The only problems that I have ever heard of involved adjustable secondary regs that were not lubricated and developed leaks, or were over lubed and experienced airflow blockages due to excess grease.

I do have a question though. Do any air rifles, except the CO2 rifles from AirForce, utilize the burst disk safety feature? A burst disk is a small bold with a hole in it. The hole is covered with foil. If the internal pressure of the gun raises above a certain point, usually 3000 psi, the foil will tear and the air is safely vented.

Hope you did not take my observation the wrong way. I learn much better “doing” then reading – so just want to clarify the point on velocities as much as possible in case any others are like me. (Probably not)

I didn’t figure it out until I bought a PCP.

I haven’t done a ton of testing yet, but your medium power setting sound pretty close to what I get.

Also don’t worry about supplying data for us to compare unless you want. I did find about a half dozen people that owned both my FX and your S410 – and the conclusion was if you want features get the S410, if you want quiet get the FX.

Accuracy wise 2/3 said not enough difference to pick a winner; the remainder gave a slight nod to the FX. But I would guess individual rifles vary enough to make it anyone’s game. They all liked both rifles.

The good news is I may want to upgrade the .22 Webley some day, so the S410 carbine is on my short list. Do you own one too?

The funny thing is that at half power it shoots the 10.2 grain at 919fps, but it only goes up to 1081fps on full power.. so half on the adjuster is not half power.

I can adjust my aiming, or the power adjuster as I loose POI. But I choose to adjust my aim and leave the power adjuster at half. That is the speed that gives the best groups with the JSB 10.2 Exact heavy. But, I can't tell if the JSB Exact 8.4 are just as accurate, they might be, it would take a long test to find out for sure.

I had two of the .22 cal carbines for a week each. Both went back to PA with bad mag advances… they didn't line up perfectly for the side lever to push in the pellet. I was so spoiled with the smoothness of my .177 that I sent them back, but now I think I could have made them work, after fixing the .177 that broke not long after I sent back the s410 carbines..

I think the carbines have a smaller air tank, so they don't get as many shots. When your ready, I would go for the full size, walnut stock. Since your my bro and cover my back for me…If you want to try one, I'll rent you either the S410 .22 cal walnut stock, or the beech stock S310 .22 cal.. for a week or two.. you still have my email, don't you?

Painball regs must be substantially different than airgun regs if they last that long.

Burst disks are not quite foil. They are thin metal plate. The ones I used to install at AirForce are round in shape and are certified from the vendor. They have to burst very close to their rated pressure throughout their life – which is indefinite.

They were installed in a copper cup that was placed into a machined seat on the side of the valve body. They were then sealed with a slotted screw (now an Allen screw, that we also made. The torque spec was in inch-pounds and it was important for them to be torqued correctly.

I saw a few that didn’t pass our air pressure test, when we tested each valve, but I never saw one fail in use, except for one that the owner pierced with an icepick because he felt it was time for the burst disk to be replaced. Sort of like ripping up the rose bushes to examine the health of the roots.

Hey BB, this is Witt, publishing as anonymous because the Google/Blogger keeps forgetting my username/password.

I just shot about 5 rounds of 5mm Crow Magnums through my Benjamin 392 by accident. It was twilight and I grabbed the wrong pellets by mistake.

A couple of questions: First, since I was essentially “dry-firing” the Benjamin, will the valve mechanism be damaged? Second, although I can’t see any damage to the bore, is it possible that the bore is damaged?

After the mistake I took the gun into my basement to shoot and the groups seem to be OK.

When you called AirForce you apparently didn’t tell them who you were. They wanted to speak to you about your rifle. The person you spoke to didn’t know about your problems with poor accuracy, so she only suggested the new cap screw.

Here is what they say to you. Put the rifle in a padded vice and shoot ten shots with the 24-inch barrel. Where they go doesn’t matter, as long as you can see them all. That will tell you whether the barrel is grouping or not.

I have a question, as well. When you switched to the 24-inch barrel did you have to elevate your scope all the way? If you did, I know what the problem is. The erector tube is floating around inside the scope. If you move the reticle back down to center it should group good again. But only do that if the scope was adjusted very high to begin with.

A regulated Talon offers the promise that AirForce never specifically made, but many thought they were getting just by adjusting the power wheel; a fully power adjustable air gun. Granted, an awsome selection of barrel lengths and calibers along with three-four choices of power source (C02, regular tank, Condor tank, Micro-meter tank)give a lot of power options, but they are specific points per choice with minimal impact by the wheel if you want consistent shots. I was looking for something to replace my CO2 power for winter shooting and still shoot at 17fpe (just the right amount of power – kinda like a TX200 22). Close options were a 12″ barrel .177 and use the stock Talon tank (~19fpe), or the 24″ barrel with a Micro-meter tank. A regulated tank can be purchased with a 1000 psi or 1200 psi regulator that can hit the power requirements right on the mark and still give a large number of shots (because of the barrel length efficiency). These tanks are readily available (e.g. JDS Airman), but they haven’t worked out the ergonomics (maybe 3.5″ longer than stock). Now if there were one of those unreliable adjustable regulators, that would truly be an adjustable power gun!

JC

PS for Jony – I don’t know what you switched to the 24″ barrel from, but you do need to keep track of screw length for barrel mounting screws. The ones for the 18″ and 24″ barrel are shorter than the ones for the 12″ barrels as the longer barrels are bigger in diameter and the screws touch the barrel when installed properly. This should not have any effect other than cosmetics unless you try to screw the longer screws in flush with the frame on a 24″ barrel. It sounds like your end cap hole needs to be retapped; I would advise avoiding further use of strength and big tools – probably best left to AirForce.

The POI on my Talon(18inch barrel) won’t start to drop until after 45 shots at 50 yards. That is with 21.1 grain Beeman Kodiaks at the power setting of 11 7.5. The first few shots after 45 shots group just a little low and after shot 55 or so the POI starts to drop rapidly. With shot #1 going 838fps and shot #45 going 762fps. So I get a 76fps spread with no loss of POI at 50 yards and an average of about 30FtLbs of energy.

That probably is not the best setting for every one else that owns an Airforce gun but for mine it is.I tried a lower power setting thinking I would get more shots per fill and lose a little velocity. When I went down to power setting 9 7.5 the POI started to drop at about shot 36-40 and then slowly drops all the way to shot 65. I just stopped at shot 65 because it never started to drop rapidly just little by little.

I have my power wheel set at 6 on my 18″ barrel Talon SS .22 and shoot JSB Exacts (15.8g) at about 900fps for 60 shots before the POI drops (and it pretty much goes away then). That was the lowest setting I could quickly get to that shot consistently. I may try to tune it a little lower to see if I could do better, but 5 is inconsistent. You are right; each one is different.

PS My 24″ barrel Talon SS .22 powered by C02 gets 650 or so shots at 735 fps before the power drops off at Power wheel setting of .5; AirForce advised to set it at 0, but I wanted to have it on something! I don’t know how many shots it gets with HPA as it blows through my backstops and bends my Field Target paddles, so I quit doing that!

B.B.:Should I call AirForce tomorrow and speak with someone else??? I sort of gave the lady a clue of who I was (my situation), I also mentioned that you recommended contacting them, and how the blog was helping me; Its true, I didn’t mentioned my shooting problem, only the hole problem… LOL… Or should I just wait???About the scope, nope, I didn’t because the shooting patterns were very erratic… Up, down, left, right… Even with the bipod!! It was less accurate with it, I didn’t used it much… Thank you sir!!Cheers,Jony

If you want to call AirForce today, they will be happy to talk with you. Tell them your name and that you are calling because of wild inaccuracy from a 24-inch barrel on a Talon SS. Tell them that you are the one who posted your problem on this blog.

I get dealer pricing, so buy and sell some stuff too.. A guy bought a disco from me and wanted it tuned by Tim at MAC 1. He does the trigger, crowns the barrel, puts a better seal on, and re-works the barrel bolt probe, and a power adjuster of sorts on the back… all for about $70 retail I think.. Since I was shipping him one, I thought why not send him another one of ours, and see how the mods work. Well, I didn’t pack them well enough, and the customers got scratched. So I called Tim and had him send a new one from his stock to the customer, and bill me. Since I have a scratched one coming back for the range, I sold the one that Tim tuned up..

The Mods Tim does, do help!! The trigger was 300% better…very crisp and about 2 lbs. Accuracy was more consistent. Number of shots was no change or maybe less. We didn’t notice much change by adjusting the new screw on the back.

A Discovery that Tim works on is on a whole different level, than a stock one. I would recommend this as a excellent starter PCP. And if you can find a barrel weight, it becomes a perfect PCP for the money.. From there go to the top like an Air Arms S410 or Volvo’s FX Whisper or the like.. With the Disco using only a 2,000 lb fill, they use the pressure in scuba tanks, below the 3,000 lbs you need for the other rifles, if you go that way.

Thanks much. I am actually on the waiting period for my first pcp. At the same time looking for a good used scuba tank. Divers recommend Luxfer brand, apparently for diving but I do not really know as far as pcps are concerned.